1. Field of the Invention
The present invention relates generally to large, heavy duty powered metal forming equipment, and more specifically to a punch holder for use with a hydraulically or otherwise powered metal forming press brake. The present punch holder provides for the transfer of mechanical force from a separate activator mechanism to operate a series of otherwise independent punch holder clamps, thereby simultaneously engaging or releasing the press brake punches held therein and greatly reducing the time required for configuration changes.
2. Description of the Related Art
Press brakes are conventionally used in metal forming, particularly for forming bends in relatively large and/or thick sheets of metal. Such brakes are almost universally actuated by hydraulics, but may be powered by other means (mechanical, electromechanical, etc.) as desired. These brakes commonly have a relatively fixed, lower table or bed which carries a metal forming die (or series of dies), and a relatively movable upper ram which holds a series of complementary punches. When the machine is activated, the ram with its punches is forced downwardly into the die or dies, bending any metal placed therebetween.
Punches and dies must frequently be changed due to material and workpiece requirements. While die changes are demanded primarily by material thickness demands, punches are subject to a broader variety of demands. A wide variety of punch profiles, and frequent changeovers, are required to address workpiece demands. With reference to the so-called European style of tooling, multiple independent punch holders function as intermediate spacers between the ram and the punches. These punch holders typically utilize two bolts per punch holder to secure a punch by means of a clamp plate. A ten foot long machine typically utilizes sixteen of these independent punch holders. Thus, it can require the loosening of thirty-two separate bolts to release the entire punch series. The installation of new tools can also require the tightening of thirty-two bolts, in order to secure the new punches. Thus, a total of sixty-four separate mechanical actions may be necessary in order to make a complete punch changeover in such a machine.
Accordingly, a need will be seen for a press brake punch holder system which activates the clamps and secures punches, by means of a single mechanism which acts simultaneously upon all of the punch clamps to secure or release the punches as desired, using a single mechanical motion. Two embodiments of the present punch holder are provided, with a first embodiment using a series of laterally disposed wedges for actuating the clamps, and a second embodiment using fluid means (pneumatic or hydraulic pressure).
A discussion of the related art of which the present inventors are aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,584,497 issued on Jun. 15, 1971 to William L. Pohjola, titled xe2x80x9cSliding Parallel Ways For Releasing Jammed Press,xe2x80x9d describes a series of wedges for installation beneath the dies of a metal forming press or the like. The wedges facilitate release of the press pressure in the event the press actuating mechanism becomes caught on dead center, or overcenter, and cannot be released using standard procedures. In this event, the wedges are knocked loose from their positions, thereby relieving the pressure in the press and allowing the press to be reset normally. Pohjola does not disclose any means of engaging or releasing a series of otherwise independent laterally disposed jaws using his wedges in a punch press, nor do his wedges act laterally, as in the present invention.
U.S. Pat. No. 3,889,515 issued on Jun. 17, 1975 to Walter J. Grombka, titled xe2x80x9cWedging Structure For Presses Or The Like,xe2x80x9d describes a similar structure to that of the Pohjola wedge assembly discussed immediately above. Grombka provides powered hydraulic means for adjusting or releasing the positions of his wedges, as well as hydraulic fluid under high pressure between the surfaces of his wedges and adjacent surfaces for reducing friction therebetween. However, the Grombka wedge assembly still functions essentially like the Pohjola assembly, and cannot operate laterally for actuating a series of punch clamps.
U.S. Pat. No. 3,965,721 issued on Jun. 29, 1976 to Gerald V. Roch, titled xe2x80x9cAdjustable Die Holder,xe2x80x9d describes the use of a series of vertically acting yedges which may be differentially adjusted to compensate for any bending of the die holder bar under-pressure during the bending operation. As in the devices described above, the Roch wedges act vertically, not laterally, and as they are disposed beneath the relatively stationary die, they do not communicate with the multiple punch holder clamps or jaws in any way.
U.S. Pat. No. 4,137,748 issued on Feb. 6, 1979 to Walter J. Grombka, titled xe2x80x9cWedging Structure For Presses Or The Like,xe2x80x9d describes a wedge system similar to that of his earlier ""515 U.S. Patent discussed further above. The wedge structure of the ""748 U.S. Patent includes sealing means capable of preventing blowout under the extremely high hydraulic pressures used. However, the system still operates in essentially the same manner as that of his ""515 patent, i. e., vertically, rather than laterally, as in the present invention, and does not provide any means of actuating a series of punch clamps.
U.S. Pat. No. 4,354,374 issued on Oct. 19, 1982 to Hideaki Deguchi, titled xe2x80x9cBending Press,xe2x80x9d describes a longitudinally acting wedge system, i. e., along the length or span of the press, for compensating for flexure of the stationary die during bending operations. The Deguchi apparatus is thus more closely related to that of the Roch ""721 U.S. Patent, discussed further above, than to the present invention.
U.S. Pat. No. 4,535,689 issued on Aug. 20, 1985 to Ladislao W. Putkowski, titled xe2x80x9cPress With Wedge,xe2x80x9d describes a system having opposed, longitudinally acting wedges which act to lift the die in the press to compensate for bending of the structure during forming operations. The Putkowski assembly is thus more closely related to that of the Roch ""721 and Deguchi ""374 U.S. Patents, than to the present invention.
U.S. Pat. No. 4,586,361 issued on May 6, 1986 to Andrei Reinhorn et al., titled xe2x80x9cPress Brake Deflection Compensation Structure,xe2x80x9d describes a wedge system disposed within the stationary bed of the press, rather than in the movable ram portion, as in the present invention. The Reinhorn et al. assembly includes a tension rod for the lower wedge, to adjust the height and bending of the lower plate in the machine. No lateral wedging or dual action for engaging or releasing a series of punch clamps is provided by Reinhorn et al.
U.S. Pat. No. 4,653,307 issued on Mar. 31, 1987 to Vaclav Zbornik, titled xe2x80x9cBending Tool,xe2x80x9d describes a press brake having a linear series of mutually adjacent vertical pins forming the bottom of the die. The pins are adjusted vertically by a wedge assembly, to achieve the desired height for the base of the die. Thus, Zbornik is only directed to vertical adjustment, and does not provide any means of lateral adjustment nor engagement with the upper punch clamps of the brake, as provided by the present invention.
U.S. Pat. No. 4,736,612 issued on Apr. 12, 1988 to Robert L. Russell, titled xe2x80x9cCompensating Die Holder,xe2x80x9d describes a wedge assembly disposed beneath the relatively stationary die of a punch press or similar machine. The two wedge components are sloped laterally, and while they move laterally relative to one another, the result is vertical adjustment of the upper wedge component, rather than lateral motion of adjusting members, as in the present invention. Russell does not disclose any means of engaging or releasing the punch clamps or jaws in an upper ram assembly, as provided by the present invention.
U.S. Pat. No. 4,895,014 issued on Jan. 23, 1990 to David L. Houston, titled xe2x80x9cFailsafe Tool Clamping System For Press Brake,xe2x80x9d describes various embodiments of a tool clamping system, including a series of laterally acting wedges for both the punch and die. However, the Houston wedges expand outwardly to release the clamping pressure on the punch and die, rather than using lateral expansion to grip the punches, as in the present invention. The present system secures the clamps to the ram by corresponding bolts, which allow the clamps to rock about the fulcrum defined by the bolts. Outward wedging pressure pushes the opposite lower clamp ends together to clamp the punches therein. Houston states that his wedge release action is safer, as loss of hydraulic pressure for driving the wedges results in the tooling remaining clamped in the machine, rather than being released. The present invention responds to this problem by using a series of relatively light springs which urge the clamps to a securing condition even though the wedge has been released. The machine operator may easily overcome the spring pressure by hand to release the tooling. Houston also cites the use of hydraulics for operating his system, but the hydraulic power acts only to drive the wedges to release the clamps, rather than providing a direct fluid action on a laterally moving plate for securing the tooling in the clamps, as provided by the second embodiment of the present invention.
U.S. Pat. No. 5,009,098 issued on Apr. 23, 1991 to Jacobus L. van Merksteijn, titled xe2x80x9cPress And Curve-Forming Means Therefor,xe2x80x9d describes various embodiments employing wedges in the bed of the machine for imparting a bend or compensating for bending loads. The van Merksteijn wedges act in two mutually perpendicular, generally horizontal planes to impart vertical adjustment to the assembly, whereas the present wedges are disposed in vertical planes to act laterally to apply or release clamping force to the upper ends of the punch clamps of the movable upper ram assembly.
U.S. Pat. No. 5,121,626 issued on Jun. 16, 1992 to John B. Baldwin, titled xe2x80x9cAdjustable Die Support For A Press Brake,xe2x80x9d describes a wedge couple having a front to back oriented slope, for adjusting the height of the die or punch assembly. While the movable portion of the wedge assembly moves generally horizontally, the result is a vertical motion, rather than a horizontal motion, as in the case of the present invention. The Baldwin mechanism is more closely related to the mechanism disclosed in U.S. Pat. No. 6,000,273 issued to the second of the present inventors (discussed further below), than to the present invention.
U.S. Pat. No. 5,390,527 issued on Feb. 21, 1995 to Susumu Kawano, titled xe2x80x9cUpper Tool Holder Apparatus For Press Brake And Upper Tool Attachable Thereto,xe2x80x9d describes a tool or punch clamp having an easily manipulable locking and unlocking lever. Kawano also discloses wedge means for adjusting the relative height of each separate tool clamp, but each of his clamps has a separate, independent wedge, unlike the single wedge assembly of the present invention for actuating a series of otherwise independent mechanisms. The Kawano wedge assemblies adjust vertically, rather than wedging horizontally, as in the present invention. Kawano teaches away from the present invention with his separate locking and unlocking handles for each clamp.
U.S. Pat. No. 5,507,170 issued on Apr. 16, 1996 to Susumu Kawano, titled xe2x80x9cUpper Tool For Press Brake,xe2x80x9d describes a variation upon the mechanism of the ""527 U.S. Patent to the same inventor, discussed immediately above. The ""170 U.S. Patent is a continuation in part of the ""527 U.S. Patent, and does not relate any more closely to the present invention than does the ""527 parent U.S. Patent.
U.S. Pat. No. 5,511,407 issued on Apr. 30, 1996 to Susumu Kawano, titled xe2x80x9cUpper Tool For Press Brake,xe2x80x9d describes yet another variation on an upper tool clamping mechanism, similar to those of the ""527 and ""170 U.S. Patents to the same inventor, discussed above. The same points raised in those discussions, are felt to apply here as well.
U.S. Pat. No. 5,513,514 issued on May 7, 1996 to Susumu Kawano, titled xe2x80x9cUpper Tool And Upper Tool Holding Device For Press Brake,xe2x80x9d describes still another variation on an upper tool clamping mechanism, similar to those of the ""527, ""170, and ""407 U.S. Patents to the same inventor, discussed above. The same points raised in those discussions, are felt to apply here as well.
U.S. Pat. No. 5,572,902 issued on Nov. 12, 1996 to Susumu Kawano, titled xe2x80x9cUpper Tool Holder Apparatus For Press Brake And Upper Tool Attachable Thereto,xe2x80x9d describes another variation on an upper tool clamping mechanism, similar to those of the ""527, ""170, ""407, and ""514 U.S. Patents to the same inventor, discussed above. The ""902 U.S. Patent is a continuation in part of the parent ""527 U.S. Patent discussed further above. The same points raised in those discussions, are felt to apply here as well.
U.S. Pat. No. 5,619,885 issued on Apr. 15, 1997 to Susumu Kawano et al., titled xe2x80x9cUpper Tool Holder Apparatus For Press Brake And Method Of Holding The Upper Tool,xe2x80x9d describes another variation on an upper tool clamping mechanism, similar to those of the ""527, ""170, ""407, ""514, and ""902 U.S. Patents to the same inventor, discussed above. The """"885 U.S. Patent is a continuation in part of the parent ""407 and ""514 U.S. Patents discussed further above. The same points raised in those discussions, are felt to apply here as well.
U.S. Pat. No. 5,642,642 issued on Jul. 1, 1997 to Susumu Kawano, titled xe2x80x9cUpper Tool And Upper Tool Holding Device For Press Brake,xe2x80x9d describes an additional variation on an upper tool clamping mechanism, similar to those of the ""527, ""170, ""407, ""514, ""902, and ""885 U.S. Patents to the same inventor, discussed above. The ""642 U.S. Patent is a continuation in part of the parent ""514 U.S. Patent discussed further above. The same points raised in those discussions, are felt to apply here as well.
U.S. Pat. No. 5,685,191 issued on Nov. 11, 1997 to Susumu Kawano et al., titled xe2x80x9cUpper Tool For Press Brake,xe2x80x9d describes a further variation on an upper tool clamping mechanism, similar to those of the ""527, ""170, ""407, ""514, ""902, ""885, and ""642 U.S. Patents to the same inventor, discussed above. The ""191 U.S. Patent is a continuation in part of yet another U.S. Patent to the same inventor, not cited herein. The same points raised in the discussions of the earlier Kawano U.S. Patents cited further above, are felt to apply here as well.
U.S. Pat. No. 6,000,273 issued on Dec. 14, 1999 to Carl Stover, titled xe2x80x9cPress Brake Punch Holder,xe2x80x9d describes a longitudinally acting (i. e., the width of the machine) wedge mechanism for securing a series of punches in a corresponding series of clamps in the upper portion of a press brake machine. The mechanism of the Stover ""273 U.S. Patent operates generally horizontally to lift a clamp actuating mechanism vertically, rather than acting laterally to apply a lateral clamp actuating force, as in the present invention. The device of the Stover ""273 U.S. Patent appears more closely related to the fore and aft wedge system of the Baldwin ""626 U.S. Patent discussed further above, than to the present invention.
U.S. Pat. No. 6,018,979 issued on Feb. 1, 2000 to Stephen B. Davis, titled xe2x80x9cTool Working Height Adjustment For Press Brake,xe2x80x9d describes a series of mating pairs of stepped wedges for independently adjusting the height of each punch relative to the ram. Each punch clamp or holder is secured to its own dedicated step wedge pair for independent adjustment. This teaches away from the present invention, with its single wedge assembly providing actuation of all of the punch clamps simultaneously. The Davis assembly is directed to individual height adjustment of the clamps and their punches, rather than providing any means for securing or releasing the punches in their clamps, as provided by the present invention.
German Patent Publication No. 616,783 published on Aug. 5, 1935 illustrates a wedge assembly acting along the width of the machine to compensate for machine structural bending loads during metal bending operations. No means for releasing the punches secured in the machine, is apparent in the drawings. The device of the ""783 German Patent Publication thus appears to be more closely related to the mechanisms of the Roch ""721 and Deguchi ""374 U.S. Patents discussed further above, than to the present mechanism.
Japanese Patent Publication No. 62-267,019 published on Nov. 19, 1987 describes (according to the drawings and English abstract) a cam actuated mechanism for simultaneously releasing or locking all of the punches (upper dies) within the upper ram of a punch press. The device of the ""019 Japanese Patent Publication includes a series of individual pivoting levers corresponding to the number of punches which may be used with the press. Each lever has a punch engaging end and an opposite cam engaging end. An eccentric cam extends along the entire width of the machine, with its lobe selectively levering the cam engagement end of each lever downwardly to lock the punch engaging end of the levers against their corresponding punches as the cam is rotated. While this system does accomplish the function of the present invention, i.e., simultaneous engagement or release of all of the punches using a single mechanism, the structure and principle of operation are completely different, in that the mechanism of the Japanese ""019 Patent Publication does not accomplish this by means of an internally and longitudinally disposed wedge assembly and pivotally mounted punch holders which are pivotally wedged outwardly to hold their corresponding punches, as is the case of the present invention.
Soviet Patent Publication No. 1,382,543 published on Mar. 23, 1988 describes (according to the drawings and English abstract) a mechanism for use in a stamping machine. A series of helically threaded clamps are tightened selectively to clamp the two plates together. Wedge adjusting means appears to be used, but the wedges appear to adjust the assembly upwardly and downwardly, i. e., vertically, rather than producing any lateral wedge action for selectively securing or releasing any laterally disposed components, as is the case in the present invention.
European Patent Publication No. 569,880 published on Nov. 18, 1993 to Amada Metrecs Company, Limited (Susumu Kawano, inventor) titled xe2x80x9cUpper Tool And Upper Tool Holding Device For Press Brake,xe2x80x9d describes essentially the same device as that disclosed in U.S. Pat. No. 5,619,885 to the same inventor, discussed further above. The ""880 European Patent Publication cites most of the same foreign applications as priority, as cited in the ""885 U.S. Patent. The same points raised in the discussions of the earlier Kawano U.S. Patents cited further above, are felt to apply here as well.
Finally, Japanese Patent Publication No. 8-057,542 published on Mar. 5, 1996 to Amada Metrecs Co., Ltd. describes (according to the drawings and English abstract) a mechanism very closely related to those of the other U.S. Patents to Kawano (assigned to the same assignee, Amada Metrecs Co.) and the ""880 European Patent Publication cited above. It is noted that the first and second inventors shown in the ""1542 Japanese Patent Publication (Toshiro Kawano and Mamoro Sugimoto) are also shown respectively as the third and second inventors in the ""885 and ""191 U.S. Patents cited further above. The same points raised in the discussions of the earlier U.S. Patents to Susumu Kawano and to the same Amada Metrecs assignee cited further above, are felt to apply here as well.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a press brake punch holder solving the aforementioned problems is desired.
The present invention is a punch holder for use with large, power operated industrial press brakes, used for bending large and/or heavy gauge sheet metal. Conventionally, such brakes use xe2x80x9cpunchesxe2x80x9d or upper tooling members removably secured within a movable upper ram assembly, which engage the sheet metal sandwiched between the punches and one or more relatively fixed dies. When it is necessary to perform a different bending operation, the punches must be removed and exchanged, with bolts typically being used to secure each punch to the ram assembly. A ten foot long machine typically requires sixteen punch holders, with each punch holder typically being six inches wide. Thus, it may be necessary to remove and replace up to thirty two bolts, if all of the punches must be interchanged.
The present invention responds to this problem by means of a single actuator which acts to simultaneously secure or release all of the otherwise independent punch clamps or holders in a single operation. Two different embodiments are disclosed herein, with a first embodiment using a laterally acting, laterally symmetrical wedge assembly for urging the upper ends of the clamps apart and thus causing the clamps to grip their respective punches as the clamps pivot about their respective fulcrums. A second embodiment uses fluid pressure (pneumatics or hydraulics) to selectively pressurize a sealed flexible chamber, thereby symmetrically applying outward lateral pressure on the upper ends of the clamps.
Accordingly, it is a principal object of the invention to provide a punch holder for a press brake, comprising a single punch clamp activating apparatus communicating with a plurality of otherwise independent punch holding clamps for simultaneously and selectively releasing the clamps by the application or release of a symmetrical lateral force against the upper ends of the pivotally mounted clamps.
It is another object of the invention to provide such a punch holder wherein the lateral force is applied by a laterally acting, symmetrical wedge assembly which selectively drives a plurality of fingers outwardly against the upper ends of the clamps.
It is a further object of the invention to provide such a punch holder wherein the lateral force is applied by a laterally acting, symmetrical fluid activated flexible chamber for applying outward pressure to the clamp actuating fingers.
Still another object of the invention is to provide a punch clamp holding and releasing apparatus including a plurality of relatively light springs for holding the clamps in a secured condition when wedge or fluid pressure is released.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.